1. Field of the Invention
The present invention relates to a vibration-damping electromagnetic actuator that generates driving force of a movable member in relation to a stator through energization to a coil, an active fluid-filled vibration-damping device that applies the force generated by the vibration-damping electromagnetic actuator to a fluid chamber in order to reduce vibration in an offset fashion, and an active vibration-damping device that reduces vibration of a member subject to vibration-damping in the offset fashion by the force generated by the vibration-damping electromagnetic actuator.
2. Description of the Related Art
From the past, for an active fluid-filled vibration-damping device, an active vibration-damping device and the like, a vibration-damping electromagnetic actuator has been used as an actuator that generates oscillation force. The vibration-damping electromagnetic actuator has a stator and a movable member displaceable relative to the stator. For those stator and movable member, one has a coil member including a coil that forms a magnetic field through energization, while the other has an armature that is displaced relative to the coil member by an effect of the magnetic field formed by the coil. Note that a vibration-damping electromagnetic actuator shown in U.S. Pat. No. 7,348,694 has a structure wherein a tubular stator provided with a coil member is externally disposed about a movable member provided with an armature.
As for U.S. Pat. No. 7,348,694, a tubular guide sleeve is disposed between the stator and the movable member, and the movable member is guided in sliding contact with the guide sleeve, whereby the movable member is smoothly displaced in the axial direction while being positioned relative to the stator in the axis-perpendicular direction.
However, with the structure of U.S. Pat. No. 7,348,694, in the case where the movable member is displaced tilting relative to the stator for example, the movable member may be in contact with the guide sleeve supported by the stator with a small contact area. This can give rise to problems such as unstable motion due to sticking, abrasion of the movable member and the guide sleeve (deterioration in durability) by an increased contact pressure, and the like.
In U.S. Pat. No. 7,348,694, the lower end part of the guide sleeve is bent to form a flange shape, and this lower end part of the guide sleeve is elastically abutted to an elastic plate on the side of the stator by a coil spring, whereby the guide sleeve is supported in such a state that the guide sleeve is allowed to be tilted relative to the stator to a certain extent. However, when the stator supports the guide sleeve via these separate coil spring and elastic plate in this way, a problem like a complicated structure due to an increase in the number of parts etc. may arise.
Additionally, with a structure wherein the flange-shaped lower end part of the guide sleeve is clamped between the coil spring and the elastic plate in the axial direction, it is difficult to have the guide sleeve supported by the stator in a stable manner, while having the guide sleeve tilted following the movement of the movable member. It is because, despite desirability of hardened compression spring between the coil spring and the elastic plate in the axial direction for realizing stable support of the guide sleeve in relation to the stator, the hardened compression spring prevents the guide sleeve from tilting relative to the stator, thereby making it difficult for the guide sleeve to follow the movable member when the movable member gets tilted.